Process and an apparatus for regulating the drive or deceleration of power driven or decelerated rollers in drawing and straightening installations

ABSTRACT

What follows is a description of a process and apparatus for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material is passed across a plurality of rollers under a stretching tension. In effecting this regulation, the variation in elongation to which the strip is subjected during its passage across a roller is measured and them compared with a preset nominal value. The comparison is then utilized for regulating the roller drive.

0 United States Patent 1 1 1111 3,889,505 Ihle June 17, 1975 1 1 PROCESSAND AN APPARATUS FOR 2.519.818 8/1950 Blain 72/2411 x REGULATING THEDRIVE on 2,526,296 10/1950 Stone .1 72/205 $559,431 2 1971 Noe et a1.72/21 DECELERATION OF POWER EN 0R 3,783,667 1/1974 Munchbach 1. 72/205DECELERATED ROLLERS IN DRAWING AND STRAIGHTENING INSTALLATIONS lnventor:

Foreign Application Priority Data Feb. 7, 1973 Germany 2305777 US. Cl.72/17; 72/19; 72/205 Int. Cl B2lb 37/06; B2lb 39/08 Field of Search72/8, 9 l9. 17. 205, 249

References Cited UNITED STATES PATENTS 11/1943 Hume .1 72/9 PrimaryExaminer-Milton S. Mehr Attorney, Agent, or Firm-Edwin E. Greigg [57]ABSTRACT What follows is a description of a process and apparatus forregulating the drive or deceleration of power driven or deceleratedrollers in installations in which a strip of material is passed across aplurality of rollers under a stretching tension. In effecting thisregulation. the variation in elongation to which the strip is subjectedduring its passage across a roller is measured and them compared with apreset nominal value. The comparison is then utilized for regulating theroller drive.

6 Claims, 2 Drawing Figures PATENTEDJUN 17 I975 SHEET FQE PATENTEDJUN171915 11869505 SHEET 2 I PROCESS AND AN APPARATUS FOR REGULATING THEDRIVE OR DECELERATION OF POWER DRIVEN OR DECELERATED ROLLERS IN DRAWINGAND STRAIGHTENING INSTALLATIONS BACKGROUND OF THE INVENTION The presentinvention relates to a process and apparatus for regulating the powerdrive or deceleration of rollers in installations in which a strip ofmaterial, preferably a metal strip, is passed under stretching tensionacross a plurality of rollers; and more particularly in drawing andstraightening installations.

In drawing and straightening installations, a metal strip is stretchedbetween a hold-back frame provided with a braked roller and a drawingframe provided with a power driven roller. This braking can beconsidered as a negative power drive. The drawing force must first beapplied to that section of the strip to be stretched as an additionaldrawing force and must then be removed from the strip via the drivenrollers as it leaves this section.

According to the rope formula (S -S 'e P a the drawing or pulling forcesacting on the end of the feed section and the beginning of the deliverysection of a strip being supplied across a roller differ by the factor ea If, for example. in drawing and straightening installations it isdesired to make the difference between the strip drawing forces on thefeed side and on the delivery side of the strip as great as possiblewith a minimum number of rollers, the friction value between the rollersand the strip must be advantageously ex ploited; while sliding of thestrip on the rollers must be avoided. Sliding not only occurs when thefriction force between the roller and the strip is exceeded, but alsowhen a longer strip section per unit of time is supplied to a rollerdriven at a constant rate of revolution that corresponds to the distancecovered by the circumference of the roller in this time. The length ofthe section of strip supplied per unit of time can be increased, forexample, through a permanent elongation imparted to the strip during itspassage over preceding rollers.

In the case of drawing and straightening installations, it is known toadapt the circumferential speed of the rollers disposed in S-frames tothe alteration of the length of the section of strip, for example, byvarying the diameter of the rollers being driven in common and at thesame rate of rotation, or by driving rollers of the same diameter bymeans of individual regulatable electomotors. It is also known toprovide differential gearing between rollers of the same diameter drivenby an electromotor, or in installations comprising rollers of the samediameter, to incorporate release clutches or electromagnetic slipclutches between these and stepdown gears. For example, in GermanOffenlegungsschrift Pat. No. 2,] 18,051 there is disclosed the use ofdifferential gearing, the output rotational speed of which is designedto be varied via the compensating gear supports by a regulating gearaccording to the nec essary increase or decrease in the rotationalspeed.

Some of the known installations are expensive and some are difficult toadapt especially during operation of the installation to the operatingconditions which may vary according to the strip to be processed.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of thepresent invention to obviate these difficulties and to provide a processand an apparatus for effecting this process which, without beingexpensive, enables regulation according to measured values while theapparatus is in operation.

This and other objects are accomplished according to the presentinvention in that in a process of the type mentioned initially, theelongation variation to which the strip is subjected as it passes acrossa roller is measured, electrically compared to preset nominal values,and the result of the comparison used to electrically influence thedrive or deceleration of at least this one roller.

A development of the present invention, therefore, consists in that theelongation variations are examined in the form of differences in thespeed of the end section of the strip on the delivery side of the rollerin relation to the speed of the end section of the strip on the feedside of the roller. And then instead of the speed of the strip sectionon the feed side of the roller, the circumferential speed of the rollerand the speed of the section of strip being delivered by the roller aremeasured and the measurements converted into electrical impulses andtransmitted in this form. During operation, should the circumferentialspeed ofthe roller and the speed of the strip section on the feed sideof the roller no longer correspond. a greater sensitivity of thedifference readings will result from taking the circumferential speed ofthe roller as a basis.

With this in mind, an apparatus for effecting the process according tothe present invention is characterized in that the circumferential speedof the roller and the delivery section of the strip are measured bymeans of measuring wheels which drive function generators supplyingelectrical impulses, the number of which is proportional to the rate ofrotation of the roller. A compan ator is provided which determines thevariations of the predetermined values and the predetermined differencein the rate of rotation as a measurement of the variation in elongation.In addition, an auxiliary drive means is provided and is adapted to becontrolled by this comparator and designed to drive electric regulatingdevices for influencing the power drive or deceleration means of therollers.

A development of the apparatus according to the present inventionconsists in that the looping angle at which the strip engages the rolleris made larger by a reserve amount than would be necessary given anaverage coefficient of friction and slip-free operation in order tomaintain a specific desired difference between the drawing forces actingon the end section of the strip on the feed side of the roller and thesection of the strip on the delivery side of the roller. In this way,even if the friction value is reduced for some reason, for example,owing to soiling or to the use of a different strip material whichproduces a smaller friction value on the material on the circumferenceof the roller, the differences in the drawing tension and thus thedrawing forces remain unchanged without any slipping occurring.

Advantageously, the presetting device for the nominal value and thecomparators for indicating the preset values and the values determined(nominal value actual value comparators) give the indications in numerical form. The possibility of reading the values continuously facilitatesoperation.

The following results were obtained by means of the present invention:without adversely affecting the cooperation between the roller and thestrip, the friction value between them may be fully exploited; thecircumferential speeds of the individual rollers and their torques maybe regulated over a wide range. and. be cause nominal values which maybe preset are proceeded from. diameter variations resulting from wear ofthe rollers or the influences of differences in the na ture of the stripmaterial as expressed. for example, by different elasticity moduli. mayeasily be taken into account.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagram illustrating a tworoller hold-back frame of a drawing and straightening installationaccording to the present invention.

FIG. 2 is a block diagram according to the present invention related toa roller of a drawing and straightening installation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a strip 3is looped about rollers l and 2 in an S-shaped manner. Thecircumferential speed of the roller 1 which is equal to the speed of thesection of strip 3 which is being supplied to this roller is measured bymeans of a measuring wheel 19, while the speed of the strip sectionbeing delivered by the roller I is measured by means of the measuringwheel 20. The circumferential speed of the roller 2 is measured by meansof the measuring wheel 21, while the speed of the strip section beingdelivered by the roller 2 is measured by means of a measuring wheel 22.The measuring wheels are in driving connection with function generators24, 25, 26 and 27. The function generators transmit a very large numberof electrical impulses per rotation of the wheels. The strip 3 is loopedabout the roller I at a looping angle a, and the roller 2 at a loopingangle (1 The roller 1 rotates in the direction of the arrow 4 in FIG. I,that is, in a clockwise direction. The roller 2 rotates in the directionof the arrow 5 in FIG. 1, thus in a counterclockwise direction. Thedrawing force S] acts on the end of the strip section on the feed sideof the roller 1, while the drawing force S2 acts on that portion of thestrip section passing between the rollers 1 and 2, that is, that portionwhich is being delivered by the roller 1 and supplied to the roller 2.The drawing force S3 acts on the strip section being delivered by theroller 2. Tensile stresses 0'] to 0'3 correspond to the drawing forcesS1 to S3. On the circumference of the roller 1, the drawing force S1increases by an amount Z1 to S2. On the circumference of the roller 2,the drawing force 82 increases by an amount Z2 to S3. To render themmore apparent, in FIG. 1, the forces and auxiliary forces which areactually acting on the strip 3 in its particular direction of movementhave been indicated in an outwardly directed position radial to thecircumference of the rollers. Specific elongation quantities correspondto the individual drawing forces. The elongation of a unit length of thestrip thus in creases with the drawing forces and with the tensilestresses corresponding thereto. The drawing forces S1 S3 correspond toelongations 61 to 3 per unit length of the strip. The elasticelongations e per unit length of the strip and the tensile stresses 0'in the strip are related by the modulus of elasticity E according to theequation 6 0'/E. Thus, 6 ol/E and c 02/E. If Ae, represents the increasein the elongation e, in the are of the strip looped about the roller 1,A6, 5 e, (0- 0' l/E. If the difference 0 0', corresponding to theauxiliary force Z. is designated as 0-,, with a strip cross section F, o=Z/F. If the length of the strip on the circumferential arc ofthe roller1 corresponding to the loop angle a is 1,, the increase in this lengthis AI|,:AE\ I 0 I|IE=Z| If the ratio of loads is selected in such a waythat S, S e a no sliding is produced even as the friction value becomessmaller. Thus, a reserve is obtained within which the reductions in thefriction value. for example, by soiling or temperature variations, arerendered harmless. To make this apparent in the diagram of FIG. 1, aminimum angle B, or B is indicated for which 5-; S, e a so that thereserve angles 7, and v representing the above-mentioned reserve areprovided over and above the actual looping angles a, and a As isapparent from the diagram represented in FIG. 1 showing two rollers, thesame relationships apply for each successive roller. In as far asdrawing and straightening installations are concerned, the samemathematical interrelationships apply to rollers of multi-roller drawingframes as for rollers of multi roller hold-back frames. As, however,apart from the creep which occurs owing to the variation in theelongation of the strip on the looped roller arc on account of thedifference In the strip drawing forces on both sides of a roller, it isnecessary to operate below the sliding limit, only the reserve regionrepresented by the reserve angles y, and in FIG. 1 is available forregulating the rates of rotation and/or the retaining or drawing torquesof the rollers. Accordingly, it is absolutely essential for this reserve region to be provided.

According to FIG. 2, the roller 1 is connected to a regulatable directcurrent motor 31 via gearing 28, stepdown gearing 29 and a motorcoupling 30. A nomi nal value presetting device 32, which is connectedto a nominal-actual value comparator 34, is engaged at a predeterminedvalue corresponding to a specific increase in elongation A6,. Thedesired regulating sensitivity is engaged by means of aregulatorprecision adjustment device 33. The function generator 24driven by the measuring wheel 19 transmits to the nominalactual valuecomparator 34 the information in the form of electric impulses regardingthe circumferential speed of the roller 1 which, as long as no slippingoccurs, is equal to the speed of the strip 3 corresponding to theelongation 6,. In the same manner, the function generator 25 driven bythe measuring wheel 20 running on the strip 3 transmits to thenominalactual value comparator 34 the data including the actual increasein elongation A6,.

The difference between the number of impulses transmitted by thefunction generator 24 and the function generator 25 gives the actualvalue of A5, which is compared in the comparator 34 with the nominalvalue which has been supplied to the nominal value preset ting device32. The direct current motor is regulated according to the result of thecomparison in the comparator 34 via a current regulator 35 and an outputstep 36 in such a manner that the actual value balances out thepredetermined nominal value with the regulating precision with which theregulator-precision adjustment device has been provided.

In devices comprising compound drives, the electromagnetic slipcouplings. servomotors or regulating gears for regulating the rates ofrotation and/or torques of individual rollers via differentials duringthe mechanical shunt, can be controlled in the same manner.

What is claimed is:

l. A process for regulating the drive or deceleration of power driven ordecelerated rollers in installations in which a strip of material,preferably a metal strip, is passed across a plurality of rollers undera stretching tension, more particularly in drawing and straighteninginstallations, comprising the steps of: measuring the variation inelongation to which the strip is subjected during its passage across asingle roller; electrically comparing the variation in elongation withpreset nominal values; and utilizing the result of the comparison forthe electrical influencing of the power drive or deceleration of atleast this one roller.

2. A process according to claim 1, wherein the elongation variations aredetermined by measuring the differences in the speed of the section ofstrip of material leaving the roller from the speed of the section ofstrip of material being supplied to the roller.

3. A process according to claim 1, wherein the elongation variations aredetermined by measuring the differences in the circumferential speed ofthe roller and the speed of the section of strip of material leaving theroller and wherein the utilization of the comparison results inconverting the compared differences into electrical impulses fortransmission.

4. An apparatus for regulating the drive or deceleration of power drivenor decelerated rollers in installations in which a strip of material,preferably a metal strip, is passed across a plurality of rollers undera stretching tension, more particularly in drawing and straighteninginstallations, comprising for each roller: measuring wheels operativelyassociated with the roller for respectively measuring thecircumferential speed of the roller and the section of strip of materialleaving the roller; a function generator connected to each wheel, eachsaid function generator supplying electrical impulses, the number ofwhich is proportional to the number of revolutions of the wheel; anominal valuepresetting device for establishing a predetermined value; acomparator receiving the electrical impulses for determining thedifference between the measurement of the circumferential speed of theroller and the section of strip of material leaving the roller andcomparing this difference to the predetermined value; and roller drivemeans receiving the comparator output for regulating the drive of saiddrive means.

5. A device according to claim 4, wherein the strip of material definesa loop angle in its engagement with each roller, said angle beingselected so that it is greater than is necessary by a reserve amountwith a given friction value and with slip-free operation occurringbetween the strip of material and the roller, and wherein because of thereserve amount a specific desired difference between the drawing forceson the section of strip of material approaching the roller and thesection of strip of material leaving the roller is maintained.

6. A device according to claim 4, wherein the nominal value-presettingdevice and the nominal-actual value comparator provide their informationin numerical form.

1. A process for regulating the drive or deceleration of power driven ordecelerated rollers in installations in which a strip of material,preferably a metal strip, is passed across a plurality of rollers undera stretching tension, more particularly in drawing and straighteninginstallations, comprising the steps of: measuring the variation inelongation to which the strip is Subjected during its passage across asingle roller; electrically comparing the variation in elongation withpreset nominal values; and utilizing the result of the comparison forthe electrical influencing of the power drive or deceleration of atleast this one roller.
 2. A process according to claim 1, wherein theelongation variations are determined by measuring the differences in thespeed of the section of strip of material leaving the roller from thespeed of the section of strip of material being supplied to the roller.3. A process according to claim 1, wherein the elongation variations aredetermined by measuring the differences in the circumferential speed ofthe roller and the speed of the section of strip of material leaving theroller and wherein the utilization of the comparison results inconverting the compared differences into electrical impulses fortransmission.
 4. An apparatus for regulating the drive or decelerationof power driven or decelerated rollers in installations in which a stripof material, preferably a metal strip, is passed across a plurality ofrollers under a stretching tension, more particularly in drawing andstraightening installations, comprising for each roller: measuringwheels operatively associated with the roller for respectively measuringthe circumferential speed of the roller and the section of strip ofmaterial leaving the roller; a function generator connected to eachwheel, each said function generator supplying electrical impulses, thenumber of which is proportional to the number of revolutions of thewheel; a nominal value-presetting device for establishing apredetermined value; a comparator receiving the electrical impulses fordetermining the difference between the measurement of thecircumferential speed of the roller and the section of strip of materialleaving the roller and comparing this difference to the predeterminedvalue; and roller drive means receiving the comparator output forregulating the drive of said drive means.
 5. A device according to claim4, wherein the strip of material defines a loop angle in its engagementwith each roller, said angle being selected so that it is greater thanis necessary by a reserve amount with a given friction value and withslip-free operation occurring between the strip of material and theroller, and wherein because of the reserve amount a specific desireddifference between the drawing forces on the section of strip ofmaterial approaching the roller and the section of strip of materialleaving the roller is maintained.
 6. A device according to claim 4,wherein the nominal value-presetting device and the nominal-actual valuecomparator provide their information in numerical form.